Impact tool



Jan- 1 1952 E. R. wHlTLEDGE 2,580,631

IMPACT Tool.

Filed May 2, 1946 3 Sheets-Sheet l INVENTOR. EDGAR R. WHITLEDGEATTORNEYS Jan. 1, 1952 `RWI-"11511165:

IMPACT TooL 3 Sheets-Sheet 2 Filed May 2, 1946 Fla@ FIG.5

INVENTOR. EDGAR R. VIHITLEDGE ATTORNEYS Jan. 1, 1952 E. R.wH1T1.EDGE

IMPACT TOOL 3 Sheets-Sheet 5 Filed May 2, 1946 INVENTOR EDGAR R.WHITLEDGE ATTORNEYS Patented Jan. l, 1952 IMPACT TOOL Edgar R.Whitledge, Mantua, Ohio, assignor, by

mesneV assignments, to Reed Roller Bit Company, Houston, Tex., acorporation of Texas Application May 2, 1946, Serial No. 666,707 j 4 Thepresent invention relates to impact clutches and tools and, moreparticularly, to portable, rotary, reversible, pressure fluid actuatedtools, such as, wrenches, nut runners and the like.

One of the principal objects of the invention is the provision of anovel and improved impact clutch comprising a driving member having arelatively large moment of inertia and a driven member having arelatively7 small moment of inertia, and highly eicient, simple meansfor causing the driving member to deliver to the driven member asuccession of torsional impulses far greater than the maximum torque ofthe driving mechanism.

Another of the principal objects of the invention is Athe provision of anovel and improved impact tool comprising a driving ilywheel or momentummember having a relatively large moment of inertia, that is, arelatively large mass offset a maximum distancefrom the center ofrotation, and a driven anvil or member having a relatively small massand moment of inertia,l in combination with highly ecient, simple meansfor causing the momentum member to deliver a successionof torsionalimpacts to the driven member.

Another of the objects oi the invention is the `provision of a novel andimproved impact clutch comprising a rotatably supported, driven memberor anvil having an external shoulder, a coaxially rotatabledrivingmember or iiywheel having a relatively large moment of inertia, andmeans including an impact member pivotally connected t the drivingmember for limited angular movement about an axis oiset from butparallel with the axis of rotation of the driven member and having ashoulder located adjacent to but adapted to trail the pivotal axis ofthe impact member with the driving member for causing the driving memberto deliver to the driven member or anvil a succession of impacts.

Another obj ect of the invention is the provision of a novel andimproved impact clutchand/or tool of the character referred to which isfully reversible.

The invention resides in certain constructions and combinations andarrangements of parts and further objects and arvantages thereof will beapparent to those skilled in the art to which the invention relates fromthe following description of the preferred embodiment described withreference to the accompanying drawings forming .a part ofthespecification in which 21 Claims. (Cl. 192-305) similar referencecharacters designate corresponding parts, and in which Fig. 1 is a sideelevational view, with portions in section, approximately on the lineI-I of Fig. 3, of a hand tool embodying the present invention;

Fig. 2 is a perspective view of a portion of the driving member of theimpact clutch shown in Fig. 1;

Fig. 3 is a sectional view, approximately on the line 3--3 of Fig. 1,showing a relative position of the mechanism following impact;

Figs. 4, 5 and 6 are -views similar to Fig. 3, but showing the parts inpositions which they occupy successively during the cycle of operation;

Fig. 7 is a view similar to Fig. 1, but showing a modied construction;

Fig. 8 is a sectional view, approximately on the line 8 8 of Fig. 7,showing a relative position of the mechanism following impact; and

Figs. 9, 10 and 1l are views similar to Fig. 8,. but showing the partsin positions which they occupy successively during the cycle ofoperations.

Although the invention is susceptible of general application and'may beembodied in various construction, it is herein shown and described "asembodied in a pressure uid actuated impact wrench. Except for the partshereinafter specifically referred to, the tool shown may be ofcommercial construction and is not shown and described in detail.

Referring to the drawings, the tool shown is designated generally by thereference chai'- acter A and comprises a reversible motor, including arotor l0, comprising radial vanes or blades Il slidably supported withinsuitable grooves formed in the rotor and through the medium of which therotor is driven by pressure fluid, preferably compressed air, admittedthereto in a conventional manner by means including a trigger actuatedvalve, only the trigger l2 of which is shown in the drawings. Since themotor per se forms no part of the present invention, no furtherexplanation is thought necessary other than pointing out that othermotors, such as electric, may be employed, as desired.

In addition to the motor already referred to, the tool of the presentinvention comprises a driven member having a relatively small moment ofinertia, a flywheel or driving member having a relatively large momentof inertia, and simple, eiiicient means for operatively connecting saidmembers whereby the driving member is caused to .successively impact thedriven member. In

the embodimentI shown, the driven member is in the form of a shaft I3rotatably supported in a bushing VI4 xedly secured in the forward end ofa clutch housing I5 detachably connected to the motor housing i6 byscrews, not shown. The reversibility of the driving means may be underthe control of a sleeve-type reversing valve il for directing 'thepressure fluid to either peripheral extremity of the conventional,lunate, expansible chamber surrounding the rotor IB. The forward endofthe shaft I3 is provided with a driving connection adapted to have anadapter, not shown, applied theretoV but which, in turn, is adapted toengage a nut, bolt, Screw or other similar member which it is desired totighten or remove. The rear or right-hand end of the shaft i3, as viewedin Fig. l, is of slightly greater di ameter and is provided with twoaxially spaced, diametrically arranged, 'i arcuately-shaped projectionsor anvils I8, I3 having radial sides 2U, 2i adapted to be impinged byradial surfaces on plate-like impact or hammer members 22, 23 forming apart of the built-up flywheel or driving member or hammer assembly,designated generally by the reference character B. The anvils I3, I3extend longitudinally of the shaft I3 and are impinged by the impactmembers 22, 23, respecftively.

The impact members 22, 23 have a relatively iarge, mass and arepivotally connected by p-ins 24, 25 to an integral cage, designatedgenerally by the reference character 26. The pins 24, 25 are locateddiametrically opposite each other with respect to the axis of rotationof the driven member I3, which member is coaxially supported withrespect to the driving or momentum member B and the rotor I0. The cage23 comprises three spaced disks 2l, 28 and 29 connected by relativelynarrow webs 33, 3l, 32,L 33 and the rear or right-hand end thereof, asviewed in Figs. l and 2, is keyed to the projecting spindle 34 of therotor Iii. The Opposite or front end of the cage 26 is rotatablysupported on the shaft I3 by a flanged bushing 35 of suitablewear-resisting material. Alternatively the cage may be of built-upconstruction.

The cage 26, as shown, is counterbored from the front end so as topermit the insertion of the anvil or rear endl of the driven member I3.The impact members 2,2 and 23 are arranged axially with respect to eachother in the cage 23, the impact member 22 being located intermediatethe disk portions 2l, 28 ofthe cage and the impact member 23 beinglocated intermediate the disk portions 23, 29 of the cage. The pin 24 isxedly secured in aligned apertures in the disks 21, 28 of the cage. Thedisk 29 is provided with apertures 36 counterbored from the front end ofthe cage to a distance equal to the thickness of the disk 21 to formapertures as continuations of the apertures in the disks 21, 28 withinone pair of which the pin 24 is located. The impact member 23 isprovided with an aperture 3l diametrically opposite the pin 25 andadapted to align with the apertures in the cage within which the pin 24is positioned. This aperture, together with the aperture 33, provides anopening whereby the pin 24 may be driven out of the cage when it isdesired to disassemble the impact member 22 for purpose of inspection orreplacement. The radial flange 33 on the bushing 35 which overlies aportion of the aperture within which the pin 24 is located preventsaxial movement of the pin toward the front of the cage in the event thepin becomes loose in the cage and the impact memi ber 23 prevents itsmovement in the opposite direction since the aperture 31 is of lessdiameter than the diameter of the pin 24.

The impact members 22, 23 are similar in construction and the pin 25 isassembled in the cage 26 in a manner similar to that in which the pin 24is assembled therein. The shoulder formed by the counterbcre in the disk29 within which the pin 25 is located prevents movement of the pintoward the rear in the event it becomes loose in the cage and the impactmember 22 prevents its movement toward the front. An aperture 39 inthedisk 22 similar to the aperture 31 in the disk 23 is provided so thatthe disks are interchangeable... thus facilitating manufacture, assemblyand maintenance of the device. The counter-bore in the disk 29 inalignment with the pin 24 merely facilitates assembly.

The impact members 22, 23 are narrower than the distance between thewebs 3S, 3l and 32, 33, respectively,v and the spaces between thedisk-like portions 21, 28, and 28, 23 within which the impact membersare positioned are slightly greater than the thickness of the members22, 23, with the result that the members 22, 23 are free to pivotbetween thel webs about the pins 24, 25, respectively. The impactmembers 22,y 23 are symmetrical about central planes passingV throughthe centers of their pivotal axes and the apertures 33, 3l,respectively, and opposite sides thereof are provided with cut-outportions 43, 4I symmetrically arranged with respect to their pivotalconnections with the cage 26. The cut-out portions 4Q, 4i are of such acharacter that they produce radial or substantially radial shoulders 42,43 on each impact member spaced from its pivotal connection with thecage 26. The shoulders 42, 43 face the pivot for the impact member uponwhich they are formed and are adapted to engage the webs of the cage 26.The shoulders 42, 43 of the impact member 23 are adapted to engage thesides 44, 45 of the webs 32, 33, respectively. The symmetricalconstruction of the cut-out portions 4U, 4I and the shoulders 42, 43Vwith respect to the pivotal axes of the impact members provides forreverse operation of the device, as will be hereinafter apparent.

The center of each impact member is provided with an` aperture 4ldefined by arcuately-shaped, alternately arranged surfaces 48, 49, 50,5I connected by radial or substantially radial surfaces or shoulders 52,53, 54, 55. The arcuately-shaped surfaces 48, 4 3 are of equal radii asare the surfaces 50, 5Iv and all have their centers on a line connectingthe centers of the pivot pin 23 and the aperture 31. The. surfaces 50,5I have a common center and the. radii thereof are smaller than those ofthe. surfaces 48, 49, the centers of which are spaced apart to provideboth the necessary clearance. for the anvil I9 and to provide ample sizefor the. shoulders 52, 53, 54 and 55. Although the radii of the surfaces50, 5I are smaller than the radii of the surfaces 4B. 49, they aresoiicient to permit, the anvil associated therewith to rotate relativeto the impact member when the member is swung to one side or the otherabout its pivotal connection with the cage 26. The construction of theshoulders 42, 43 and the webs ci the cage 26 with which they engage issuch that Vthe impact members may move a sufficient dis- -With whichthey cooperate.

The operation of both impactmembers 22, 23

is alike, therefore, it will be sufficient to describe only theoperation of the impact member 23. Assuming that the flywheel ormomentum member B is rotating in a clockwise direction, as indil catedby the arrow R. the respective parts are shown in Fig. 3 in a positionwhich they may occupy shortly after impact between the shoulder orsurface 52 of the impact member 23 with the surface or shoulder 20 ofthe anvil I9. When the shoulder or surface 52 of the impact memberstruck or impacted the shoulder 20 of the anvil I3, see Fig. 6, theimpact member 23 was rotated by the reaction produced, acting in thedirection of the force arrow 60, in a clockwise direction about the pin25 until the shoulder 42 struck the side 44 of the web 32. This movementof the impact member 23 allowed the shoulder 52 and the surface 50 topass around the anvil I9. As the shoulders 20, 52 disengage, theflywheel proper accelerates. member is preferably offset with respect tothe axis of rotation of the clutch proper and the inertia of the impactmember causes it to tend to lag behind the cage 23.

As soon as the surface 50 passes the rear end of the anvil I9 defined bythe radial surface 2|, which it is about to do, as shown in Fig. 3, theimpact member 23 will be free to rotate in a counterclockwise directionabout the pin 25. At this time the flywheel proper is accelerating anddriving the impact member 23 through the pin 25. The effect of inertiaof the impact member 23, as previously mentioned, causes the member tolag .behind the flywheel proper whereupon the impact member will movefrom a position with the shoulder 42 in engagement with the web 32 shownin Fig. 3 to a position with the shoulder 43 in engagement with the web33. The parts then will be in the approximate position shown in Fig. 5and the surface 52 again in position to impinge the surface 20 of theanvil I9.

The method of operation just described is automatic but being subject tofrictional drag between the parts, it is not positive, and to insureproper setting up of the impact member for the primary impact, theimpact member 23 is provided with the internal radial surface orshoulder 54 which cooperates with the surface 20 on the anvil, ifnecessary, to assure proper resetting of the impact member. As shown inFig. 3, the arcuately-shaped surface 50 is about to complete its passageover the anvil I9 and the radial surface 54 is approaching the impactsurface 20 of the anvil and in the event the impact member 23 has notbeen reset by inertia, as explained before, and the shoulder 43 not inengagement with the web 33, by the time the shoulder 54 reaches theshoulder 2U, the shoulder 54 will impact or strike the shoulder 20, asindicated in Fig. 4. The anvil I 9 will offer resistance to rotation ofthe flywheel proper and will act against the shoulder 54 to rotate theimpact member in a counterclockwise direction about the pin 25 until theshoulder 43 strikes the web 33. From the foregoing, it will beunderstood that the primary purpose of the shoulder 54 engaging theshoulder 20 is to assure proper setting of the impact member shoulder 52into impact delivering position relative to the anvil shoulder 2B.

The force exerted by the anvil i3 against the member 23 will act in thedirection indicated by the force arrow 6l and will have a moment arm ofmagnitude E2 about the center of the pin 25. As the member 23 rotatesabout the pin 25, the shoulders 20,154 Awill be disengaged andthe Thecenter of mass of the impact arcuately-shaped surface 5I will bepermitted to pass about the anvil I9, see Fig. 5, lwhereupon theflywheel continues to rotate freely until impact is made between thesurfaces or shoulders 20, 52, see Fig. 6. The condition existing whenthe shoulder 52 strikes the shoulder 20 is somewhat similar to thatexisting when the shoulder 54 strikes the shoulder 20 shown in Fig. 4but the moment arm 63 of the impact force about the center of the pin 25is much shorter than the moment 'arm 62, with thevvresult that theimpact or blow delivered to the anvil I3 is considerably greater and hasconsiderable force.

It will be noted that the power is transmitted to the impact memberthrough the pivot pin 25 and that the shoulder 52 is adjacent to buttrails the axis about which the impact member is pivoted to the drivingmember o'r flywheel proper. By varying the radial position of the pivotwith respect to the shoulder 52, etc., or by varying theangular positionof the shoulder 52 with respect to the pivot, the moment arm 53 can beincreased or decreased to Vary the blow imparted to the anvil. The sameis true of the shoulder 54 which,`as shown, leads the pivot for theimpact member. When the shoulder 52 strikes the shoulder 20 of theanvil, the reaction pro-- duces a clockwise acceleration of the impactmember 23 about the pin 25 which because of the relatively large mass ofthe impact member, adds to the fore of impact, moves the shoulder 42into engagement with the surface 44 of the web 32, disengages theshoulders 20, 52 and permits the'ywheel to resume rotation about theanvil. While the engaging surface 52 and 54 on the impact member 23, and2l) on the anvil i9, respectively, are preferably radial, they may bevaried slightly from a true radial position so as'to facilitate theirdisengagement and eliminate all possibility of their hanging together,if desired.

The rotation of the impact member 23 about the pin 25 following impactbetween the shoulders 20,352 occurs with considerable acceleration andas the member 23 reaches its limit of movement by the shoulder 42engaging or striking the web 32, the kinetic energy possessed by theimpact member is transferred back to the rotating flywheel and serves toreduce the load of the flywheel upon thedriving motor, thus permittingthe motor to accelerate and build up speed rapidly between successiveimpacts. When impact occurs between the shoulders 20, 54 incident tosetting up or preparing the impact member for the power or primaryimpact which takes place when the shoulder 52 strikes the shoulder 20,it occurs only because the frictional forces which may be present resistthe automatic counterclocku wise movement of the impact member thatwould otherwise afford uninterrupted passage of the member about theanvil between successive primary impacts. The energy used in thissetting-up impact is small, being much less than that imparted by theflywheel or hammer to the anvil upon impact between the shoulders 20, 52for the moment arm 52 at which the set-up force acts is much greaterthan the moment arm 53, and the direction of motion of the shoulder 54is nearly collinear with the force arrow 6I, Whereas the direction ofmovement imparted to the 'shoulder 52 is almost perpendicular to theforce arrow 50. Observation of the device in operation indicates thatthe impact member is frequently set up for the `power impactautomatically. by the .inertia thereof, as previously explained,

.the surface or shoulder 2S cf the anvil i and without Contact. betweenthe shoulders 20 54.. The anvils' i5, i9, and the. pivots for the im*nactmembers 22, 23 are Offset 1.80 degrees. and. two power blows orimpacts which act as a couple are @Heated 'upon each rotation ofthevfis/wheel assembly E. Qbvouslv'anv number of impact members and anvilsmay beeniployed, inwhich event any desired number of impacts will beObtained for each rotation of the iiywheel,

The anvils i9 and the impact members 22, 23 are symmetrical with`respect to a central plane, from which 'it 'fellows that the clutch oroperative connection betvvee'nthe driving inember B and the drivenmember i3 is reversible, therefore, it is only necessary to employ areversible motor and 'the tool, iS suitable for tightening or locsening'nuts,'bclts, screws and the like. Referring tothe operation ci the'impact member 23, when the drive is reversed the shoulders 2l, 53 and'correspond with the shoulders 2t, 52 and til,'respectively` With theexception of the driving element ci the clutch, the alternativeconstruction shown in Figs. 7 to ll is similar to that already describedand the duplicate parts are indicated by the'sa'me reference characters.As distinguished from the construction shown in Figs. l to 6 wherein theimpact members 22, 23 are pivotally supported in an integral cage 26,the impact members 55, d5 of the alternative construction are disk-likein form and are pivot-ally connected to diametrically arranged sleeves67, 6d interposed between spaced plates lil, Il iixedly secured togetherso that they operate as a unit by bolts l2, '.'3 ex tending through thesleeves 6l, iid, respectively.

The plate li is keyed to the end 35 of the ro tor SG and the plate illis rotatably supported by the shaft is. The sleeves 6l, 68 are slightlylonger than the dish-like impact members 65, 6G, are thick, thuspermitting each member tc move about the sleeve to which it is pivoted.Beth impact ineinbers G5, @E are alike and each is provided with anarcuateiy-shaped slot 'l through which the sleeves other than the sleeveto which the member is pivcted projects. The midpoint of each of theslots le is located lSc degrees from the axis about which the disk ispivoted, which axis' also forms the radial'ccnter of the slct.

ln the center of each disk there provided an aperture 'iii similar inconfiguration to theaper tures il? previously described'and dened bysimi lar arcuately-shaped and radial surfaces deu signated by the samereference characters slots are of such length that the impact inem.-bers are permitted a limited movement about the sleeves upon which theypit'oted. which movement is suficientto cause the radial sin-u lacesthereon to engage and disengage the radial surfaces of the'anvil withwhich they cooperate.

The operation of both impact members 65, 35 is alike, therefore, it willbe suicient to describe only the operation of the impact member B5.Assuming that the flywheel or momentum member B is rotating in thedirection indicated by the arrowY R, the respective parts are shown inFig. 8 in a position which they may occupy shortly after the primaryimpact between the shoulder or surface 52 of the impact member Sii withWhen the shoulder or surface 52 of the impact mem- 'ber struck orimpacted the shoulder 23 of the anvil i8. see Fig. 11, the impact memberwas rotated by the reaction produced, acting in the Vdirection of" thevforce arrow til, in a clockwise direction. about-the sleeve`G'I--un-tilthe trailing accuser end of the slot 1 4 contactedthe'sleeve 88. This movement of `the impact member 65 allowed theshoulder 52 andthe surface 50 to pass around the anvil i8. As theshoulders 20, 52 disengage, the iiywheel proper accelerates. The centerof mass of the impact member is offset with respect to the axis ofrotation of the clutch proper and the inertia of the impact membercauses it to tend to lag behind the flywheel proper.

As soon as the surface 50 passes the rear end of the anvil I8 defined bythe radial surface 2i. which it is about to do,l as shown in Fig. 8, theimpact member 65 will be free to rotate in a counterclockwise directionabout the sleeve S1. At this time the flywheel proper Vis acceleratingand driving the impact member through the sleeve El. TheV effect of theinertia of the irnpact member 65, as previously mentioned, causes themember to lagv behind the flywheel proper until the leading end of theslot 14 engages the sleeve 58, that is, the impact member B5' wi1 l movefrom the position shown in Fig.' 8 to the approximate position shown inFig. l and the surface 52 will be in position to iinpinge the surface 20of the anvil I8.

The foregoing method of operation is automatic but because of thevariable fricticnal drag between the parts, it is not positive and toinsure proper setting up of the impact member for the primary impact,the impact member E is provided with the internal radial surface orshoulder 5ft which cooperates with the Surface 2 0 on the anvil, ifnecessary, to assure proper resetting of the` impact member. As shown inFig! 8., the arcuately-shaped surface 50 is about to complete itspassage over`- the anvil i8 and the radial surface 54 is approaching theimpact surface of the anvil and in the. event the impact. member 5.5 hasnotv been'reset by inertia,

as explained above, by the time the shoulder 51S reaches the shoulder20, the shoulder 5,4 vwill impact or strike the shoulderV 23, asindicated in Fig. 9. The anvil I3 will offer resistance to rotation ofthe ywheel proper and will act ,f against theV shoulder 54 to rotate thevimpact member in a counter-clockwise direction about the sleeve Eluntil the leading end of Vthe. slot lll' engages the sleeve 68.A

The force exerted by theanvil le against the member will act in thedirection indicated by Vthe force arrow 6lv and willv have a moment. armcf magnitude 62 about the center of the sleeve el. As the member E5rotates4 about the sleeve 6 1, the shoulders 2,0, 54 will be disengagedand the arcuatelyeshaped surface 5 lr will be permitted to pass about,the anvil I8, see Fig. 10., whereupon the flywheel continues. to rotatefreely until impact. is made between the4 surface or shoulders 2l), 52,see Fig. 1l. The condition` existing when the shoulder 5,2 strikes theshoulder 2,0

is similar to that existing whenfthe shoulder 54 strikes the shoulderY2G shown in Figi 9, but the moment arm 63 of the impacty force about thecenter of the sleeve 671 is much shorter than the moment arm 62, withthe result that the impart or blow delivered to the'anvil i8 is c onsiderablyr greater and has considerable force.

When the shoulder 5K2` strikes the shoulder 2c of the anvil, thereaction produces. a clockwise acceleration of the impact member 65about the sleeve 6lV which. because ofl the. relatively .large massv ofthe. impact member, adds to the force of impact, moves` the. trailing`end ofy the slot 'I4 into'. engagement. with the-sleeve 6 8; dis.-gengages; thel shoulders 2.0, 52` and` permits .the-fly,-

wheel to resume rotation about the anvil. While the engaging surfaces 52and 54 on theimpact member 65 and the surface 20 on the anvil I8,respectively, are preferably radial, they may be varied slightly from atrue radial position Yso as to' facilitate their disengagement andeliminate all possibility of their hanging together, if desired. Theshoulder 52, as shown, is adjacent to but trails the axis about whichthe impact member is pivoted to the driving member or iiywheel properand the moment arm 63 can be increased or decreased to vary the blowimparted to the anvil by varying the relative radial position of thepivot with respect to the shoulder 52, etc., or by varying the relativeangular position of the shoulder 52 with respect to the pivot. The sameis true of the shoulder 54 which. as shown, leads the pivot for theimpact member.

The rotation of the impact member 65 about the sleeve 51 followingimpact between the shoulders 20, 52 occurs with considerableacceleration and as the opposite or trailing end' of the slot I4 strikesthe sleeve 68, the kinetic energy possessed by the impact member istransferred back to the rotating flywheel and serves to reduce the loadof the flywheel upon the drivingr motor, thus permitting the motor toaccelerate and build up speed rapidly between successive impacts. Whenimpact occurs between the shoulders 20, 54 incident to setting up orpreparing the impact member for the power or primary impact, it occursonly because the frictional forces which may be present resist theautomatic, counterclockwise movement of the impact member that wouldotherwise afford uninterrupted passage of the member about the anvilbetween successive primary impacts. The energy used in this setting-upimpact is small, being much less than that imparted by the flywheel orhammer to the anvil upon impact between the shoulders 20, 52, for themoment arm 52 at which the set-up force acts is much greater than themoment arm 63, and the direction of motion of the shoulder 54 is nearlycollinear with the force arrow E I, Whereas the direction of move mentimparted to the shoulder 52 is almost perpendicular to the force arrow60. Observation of the device in operation indicates that the impactmember is usually set up for the power impact automatically by theinertia thereof, as prev iously explained, and without contact betweenthe shoulders 20, 54. The anvils I8, I9 and the pivots for the impactmembers 22, 23 are oiset I 80 degrees, and two power blows or impactswhich` act as a couple are effected upon each rotation of the iiywheelassembly B. Obviously any number of impact members and anvils may beemployed, in which event any desired number of impacts will be obtainedfor each rotation of the flywheel.

The anvils I8, I9 and the impact members 65, 66 are symmetrical withrespect to a central g plane, from which it follows that the clutch orFrom the foregoing description of the preferred embodiment of theinvention, it will be apparent that a novel and improved impact tool hasbeen in said aperture engageable with said anvil for' provided wherebyan impact of considerable force can be applied to a nut, bolt, screw orthe like by a relatively light tool. The tool shown is simple inconstruction, inexpensive to manufacture, will operate satisfactorilyfor long periods of time with minimum wear and replacement and producesa maximum torsional blow for a predetermined size and weight. While thepreferred embodiment of the invention has been described in considerable detail, the invention is not limited to the particularconstruction shown and it 'is my intention to hereby cover alladaptations., modi fications and uses thereof which come within thepractice of those skilled in the art to which the invention relates andwithin the scope of the ap pended claims.

Having thus described my invention, I claim:

1. In an impact driving connection, the 'combination of a rotatablysupported driven member having an anvil, a rota-table driving membercoaxially supported with respect to said driven member, a hammer elementpivotally connected to said driving member for rotation therewith andangular movement relative thereto about an axis offset from but parallelwith the axis of rotation of said driving member, said hammer elementhaving an impact shoulder located between said axes and positioned so asto always trail its pivotal connection, and movable into and out of thepath of said anvil for delivering a succession of impacts thereto,automatic means for eifecting angular movement of said impact shoulderinto the path of said anvil, and means responsive to the impact of saidshoulder on the anvil for automatically effecting angular movement ofsaid shoulder out of the path of said anvil in the same direction asthat of said driving member.

2. In an impact driving connection, the combination of a rotatablysupported driven member having an anvil, a rotatable driving membercoaxially supported with respect to said driven member, a hammer elemententirely surrounding said anvil and connected to said driving member forrotation therewith and pivotal movement relative thereto about an axisoffset from but parallel with the axis of rotation of said drivingmember, the interior of said hammer element having a shoulder locatedbetween said axes and movable into and out of the path of said anvil byvirtue of said pivotal movement for delivering a succession of impactsto `said anvil, automatic means for effecting pivotal movement of saidshoulder into the path of said anvil, and :means responsive to theimpact of said shoulder on the anvil for automatically effecting pivotalmovement of said shoulder out of the path of the anvil.

3. In an'impact driving connection, the combination of a rotatablysupported driven member having an anvil, a rotatable driving membercoaxially supported with respect to said driven member, a hammer elementconnected to said driving member for rotation therewith and pivotalmovement relative thereto about an axis offset from but parallel withthe axis of rotation of said driving member, an aperture in said hammerelement into which said anvil extends and pro# viding a first shouldermovable into and out of the path of said anvil by virtue of said pivotalmovement for delivering a succession of impacts to said anvil, saidfirst shoulder being moved out of the path of said anvil by virtue ofits impact thereon, and means including a second shoulder moving saidfirst shoulder into the path of said Aanvil.

4. An impact driving connection comprisingv a rotatablysupported.driven` member, a rotatable driving member coaxially supported withrespect to said driven. member, acylindrical hammer carrier betweensaid. members connected to4 said driv ing member for rotation therewith,an. anvil on said driven` memberand within said carrier, a hammerelement pivotally connected. to said earrier for rotation therewith andpivotal movement relative thereto about an axis offset from but parallelwith the axis of rotation ofv said carrier, an aperture in said hammerelement into which said anvil extends and providing a shoulder movableinto and out of the path of said anvil by virtue of` said pivotalmovement. for delivering a succession of impacts to said anvil,automatic means for eiiecting pivotalr movement of said shoulder intothe path of said anvil, and means responsive to the impact of saidshoulder on the anvil for automatically eiectingV pivotal movement ofsaid shoulder out of the path of theV anvil.

5. An impactI driving connection comprising a rotatably supported drivenmember, a rotatable driving member coa-Xially supported with respect toVsaid driven member, a cylindrical hammer car rier between said membersconnected' to said driving member for rota-tion therewith, a pair ofaxially spaced and diametrically opposed anvils on said driven memberand within said carrier, a hol-low hammer element surrounding eachvanvil and pivotally connected to said carrier for rotation therewith andpivotal movement relative thereto, each hammer element having aninternal shoulder movable into and out of the path of its respectiveanvil by virtue of said pivotal movement for delivering a succession ofimpacts to said anvil, and means in said carrier for limiting thelpivotal movement of said hammer element.

6*.y An impact driving connection comprising a rotatably supporteddri-ven member having an.

ing the rotation of said hammer element for f automatically effectingpivotal movement of said hammer element, said means includingr ashoulder movable into and out of engagement. with said anvil by virtueof said pivotal movement for delivering a succession of impacts to saidanvil.

'7. An impact driving connection comprising a rotatably supported drivenAmember havingr an anvil, a rotatable driving member coaxially supportedwith respect to said driven member, a hammer element connected to saiddriving meniber for rotation therewith and pivotal movement relativethereto, an aperture in said element into which said` anvil extends, andmeans on the wall of said aperture adapted to engage said anvil duringthe rotation of said element for auto-r matically effecting its pivotalmovement, said means including ashoulder movable into and out ofengagement with said anvil by virtue ofk said pivotal movement fordelivering a succession of impacts to said anvil.

8; An impact driving connection comprising a rotatably supported drivenmember having an anvil, a rotatable drivingmember coaxial-ly su1o-Vported with respect to said driven member, a

hammer element connected to said driving mme. f

lf2 ber for rotation: therewith. and pivotal movement relative thereto,an aperture in said. element. into which said anvil. extends, and.substantially dametrically opposed. internal shoulders on said 'elementadapted. to engage said anvil during the rotation of saidelement. forautomatically im partingv a succession of. rotary impacts to said anviland effecting the pivotal movement of said element.

9. An impact driving connection according to claim 8 in which saidinternalshoulders are. lo cated one to trail and the other to leadV theconnectionY between the hammer element and the driving memben l 10. AnYimpact drivingconnection comprising' a rotatably supported. member'having an. anvil, a rotatable driving. member coaxially supported withrespect to said driven member, a hammer element connectedto said drivingmemberV for rotation therewith and pivotal movement relative thereto,and a duality of substantially diamo-t# rically opposed shoulders onsaid elementvadapted toalternately strike said` anvil during normalrotation. of the. element whereby the striking shoulder is immediatelyshifted out off the path of thel anvil by virtuev of the impact and theope posed shoulder is automatically moved into` the path of the anvilpreparatory' to thenext impact 1l. An impact driving connectionaccordingI to'4 claim 10 in which. said internal' shoulders are: lo-ncated. one to trail and. the: other' to lead the corr4 nection betweenthey hammer element andy the drivingv member. f

12. An impact driving connection cinpris'ing' a rotatably supported.driven'- member having an anvil, a rotatable. driving member coaXia-llystip-f ported with respect to said driven' member, a

hammerelement connected to said driving member forrotation therewith andpivotal movementl relative thereto, and a duality of shoulders onv said.element adapted to alternatelystrike. said anvil. during normal rotationof the element, said anvil and shoulders having striking faces shapedand disposed relative to thexconnection between" the hammer element andthe driving member whereby each impact automatically effects movement ofthe striking shoulder out of the path of the anvil 'and movement' of theother shoulder into the path. of the anvil preparatory to the nextimpact.

13. An impact driving connection comprising a. rotatably supporteddriven memberhaving an anvil, a rotatable driving member coaxiallysupported with respect to said driven member, a hammer element connectedto said driving' member for rotation therewith and pivotal movementrelative thereto, and means for effectingA the pivotal movement of saidelement including a striking shoulder and a resetting shoulder on saidelement one located on one side and the other one the other side of theconnection between said element anddriving member, said shoulders beingadapted to alternately strike said anvil during normal rotation oftheelement for impart1 ing a succession of rotary impacts to said anvil,

said striking shoulder being located closer to saidl connection than theresetting shoulder.

14. An impact driving connection according toclaim 13 in which lthestriking shoulder is located` to trail said connection.

15. An impact driving connection comprising nected to said-drivingmember for rotation there-` with in either direction and pivotalmovement relative thereto, said element having two sets of twoshoulders, one set of shoulders being adapted to engage said anvilduring normal rotation of the element in one direction and the other setof shoulders being adapted to engage said anvil during normal rotationof the element in the other direction for automatically effecting itspivotal movement and imparting a succession of rotary impacts to saidanvil.

16. An impact driving connection according to claim 15 in which theshoulders of each set are located one ahead and one behind theconnection between said element and driving member with respect to thedirection of rotation of said element.

17. An impact driving connection according to claim 15 in which theshoulders of each set are located one ahead and one behind theconnection between said element and driving member with respect to thedirection of rotation of said element, the shoulder of each set locatedbehind said connection being closer thereto than the shoulder aheadthereof.

18. An impact driving connection comprising a rotatably supported drivenmember, a radially extending striking face on said member, a rotatabledriving member, a hammer element, a connection between said drivingmember and element affording rotation of the element with the drivingmember and relative angular movement therebetween about an axis offsetfrom but parallel with the axis of rotation of said driving member, saidhammer element having a shoulder movable into and out of the path ofsaid striking face by virtue of said angular movement for delivering asuccession of impacts thereto, at the time of impact said shoulder beingparallel with said striking face and located behind said connection withrespect to the direction of rotation of said driving member, andinterengaging means between said element and driven member automaticallyeffecting angular movement of said shoulder into the path of saidstriking face, said shoulder being moved out of the path of saidstriking face by virtue of its impact thereon.

19. An impact driving connection comprising a driven element and adriving element rotatably supported on parallel axes, an aperture insaid driving element into which said driven element extends, saiddriving element being capable of intermittent driving connection `withsaid driven element, and means in said aperture between said elementsautomatically eiecting and breaking said connection during eachrevolution of said driving element including a shoulder externally onsaid driven element and a shoulder internally on said driving element.

20. In an impact driving connection, the combination of a rotatablysupported driven member having an anvil, a rotatable driving membercoaxially supported with respect to said driven member, an impact memberpivotally connected to said driving member for angular movement about anaxis oilset from but parallel with the axis of rotation of said drivenmember, said impact member having a shoulder adapted to impact saidanvil, said shoulder being arranged and disposed in a manner enabling aline normal thereto at the time of impact to pass through the pivotalcon nection between the impact and driving members.

21. In an 'impact driving connection, the combination of a rotatablysupported driven member having an external shoulder, a rotatable drivingmember coaxially supported with respect to said driven member, an impactmember, a pin pivot ally connecting said impact member to said drivingmember for angular movement about an axis oiset from but parallel withthe axis of rotation of said driven member, said impact member having ashoulder adapted to impact said shoulder on said driven member, saidshoulder being disposed in a manner enabling a line normal thereto atthe time of impact to pass through said pin.

EDGAR R. WHITLEDGE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Richards Sept. 24, 1946

